There's a New Planet in Sight

A computer-generated image of TrES-2. TrES-2 is a gas planet like Jupiter, but it is larger.

Illustration courtesy Lowell Observatory

A computer-generated image of TrES-2 crossing its home star.

Illustration courtesy Lowell Observatory

Catherine Clarke Fox

An international team of astronomers has discovered a planet slightly larger than Jupiter that orbits a star 500 light years from Earth. A super-duper telescope was not even required; they found the planet using several small telescopes much like those used by amateur astronomers.

The new planet is named TrES-2 because it is the second such planet found by scientists working on the Trans-Atlantic Exoplanet Survey (TrES). It is a transiting planet, meaning it can be seen transiting, or moving, across the star it orbits.

Ted Dunham, an instrument scientist at Arizona’s Lowell Observatory, says transiting planets are special because researchers can answer a lot of questions about them. All it takes is some math and some observations about the planet and its relationship to its star.

Some key questions: How big is it? How long is its year (the time it takes to orbit around its star)? How much would you weigh if you were there?

“TrES-2 is a little bigger than Jupiter, has a ‘year’ that is a little less than two and a half days, and is a little more massive than Jupiter,” explains Dunham.

From its mass and radius (the distance across the planet) scientists can figure out the density of the planet—whether it is made of rock, gas, or a combination of the two. (TrES-2 is made up mainly of gas).

They can also work out the surface gravity, says Dunham: “You would feel a little more than twice as heavy as on Earth if you were on TrES-2.”

There’s a catch, though. “The temperature is about 1,500 degrees Celsius (2,732 degrees Fahrenheit), and there is nothing solid to stand on. It isn’t a likely place to look for life,” he says.

Dunham says that to find smaller planets like Earth or Venus, scientists need to send instruments on a mission to space. NASA scientists are planning one called the Kepler Mission, which could begin in two years.

TrES-2 is in the part of the sky that the Kepler Mission will study. Since astronomers already know so much about it, they can use it to help make sure their instruments are working.

“It’s really a blast to be working on finding planets orbiting other stars,” says Dunham. “People have wondered for millennia whether there are other planets like ours, maybe with living things on them. The next ten years should be fun. Stay tuned!”